Free sphingosine in human epidermis.
The aim of the present study is to determine the concentration and composition of free long-chain bases in human stratum corneum. Samples of foot callus obtained from a local chiropodist were extracted at room temperature with chloroform: methanol mixtures (2:1, 1:1, and 1:2). The extracts were concentrated, filtered to remove nonlipid debris, and dissolved in chloroform: methanol, 2:1, at a concentration of 25 mg/ml. Small portions of extract were treated with 2,4-dinitrofluorobenzene to convert free amino groups to N-dinitrophenyl derivatives, which were subsequently separated from other components by thin-layer chromatography (TLC) and quantitated by photodensitometry at a wave-length of 355 nm. The N-dinitrophenylsphingosines were then isolated by preparative TLC and oxidized with lead tetraacetate in benzene to produce aldehydes, which were analyzed by gas-liquid chromatography. It was found that callus lipid contained 3.39 +/- 0.57 mg free sphingosine, 1.60 +/- 0.72 mg dihydrosphingosine and traces of phytosphingosine per g lipid. The sphingosines and dihydrosphingosines ranged from 16 through 20 carbons in length, with 18:1 as the predominant constituent. These findings are similar to those recently reported for pig epidermis and support the possible role of free sphingosine as a regulator of epidermal differentiation.
Wertz
P W
PW
Department of Dermatology, University of Iowa College of Medicine, Iowa City 52242.
Downing
D T
DT
D002146:Bony Callus / Q000378:metabolism; D002849:Chromatography, Gas; D003720:Densitometry; D005528:Foot; D006801:Humans; D012867:Skin / Q000032:analysis*; D013110:Sphingosine / Q000032:analysis*
D013110:Sphingosine